Antitumor activity and immunomodulation mechanism of a novel polysaccharide extracted from Polygala tenuifolia Willd. evaluated by S180 cells and S180 tumor-bearing mice

We recently isolated a polysaccharide from Polygala tenuifolia Willd. (PTP) and reported that such a PTP could induce cell apoptosis with FAS/FAS-L-mediated death receptor pathway in human lung cancer cells. Herein, we indicate antitumor activity and immunoregulation of PTP for S180 sarcoma cells by in vitro and in vivo targeting. In vitro, S180 cells took on prominent characteristics of apoptosis under-treated with PTP in follow-up antitumor activity studies, including irregular shrinkage and fragmentation nuclear, apoptotic bodies formation, and reduction of mitochondrial membrane potential (MMP). Additionally, flow cytometry indicated that the number of normal cells (FITC-/PI-) gradually decreased from 98.08% to 16.31%, while the number of apoptotic cells (FITC+/PI- or FITC+/PI+) increased from 0.87% to 54.84%. The ratio of BAX and Bcl-2 increased, which promoted the release of Cytochrome C (CytC), and it further maximized the expression of activated-caspase-9/-3. Additionally, the PTP revised the immune organ indexes, the activities of NK cells and lymphocytes, and induced the secretion of IL-2 (7.34-16.17%), IFN-γ (14.34-20.85%) and TNF-α (12.32-22.58%) in vivo. Thus, PTP can induce cell apoptosis and activate the immunoregulation mechanism thereby exhibiting biological activity.